In recent years, many kinds of airbags have been installed as a passenger safety device for automobiles. Examples of airbags include an airbag for a driver's seat, an airbag for a passenger's seat, an airbag for thigh protection built in a seat, a curtain airbag deploying along a side window and the like. For a base fabric constituting an airbag, base fabrics made from a polyester fiber, which is inexpensive in raw yarn cost than a polyamide fiber, have been desired. However, airbags having sufficient properties have not been obtained from a polyester fiber, compared to ones from polyamide fiber. Therefore, polyamide fibers such as nylon 6,6, and nylon 6 have been mainly used for base fabrics.
The basic fabric needs to have many kinds of mechanical properties required, in addition to deployment property, for receiving a passenger. To satisfy these requirements, for example, WO 2012/26455 proposes a base fabric intended to have high pressure resistance in a boundary portion between an inflation part and a non-inflation part and to restrain a passenger by quickly grasping him/her. Also, JP 2001-114051 A proposes a base fabric intended to have an improved deployment property while ensuring mechanical properties as an airbag by changing the warp density and the weft density. Also, JP 2000-328388 A provides a method of manufacturing a high density woven fabric intended to satisfy low air permeability, weaving properties, productivity for a base fabric for airbag.
All of the base fabrics specifically disclosed in WO 2012/26455, JP 2001-114051 A and JP 2000-328388 A are polyamide fabrics made from fiber such as nylon 6,6, and practically no polyester base fabric has been disclosed.
It could therefore be helpful to provide a polyester base fabric that assures that an airbag with improved restraint performance to receive a passenger at the time of deployment can be manufactured while ensuring mechanical properties as an airbag even though it is made of polyester, a polyester airbag produced by sewing the polyester base fabric, and a method of manufacturing the polyester base fabric.